Description and History

NPL Listing History

NPL Status: Final

Proposed Date: 12/01/00

Final Date: 09/07/02

Deleted Date:

From 1943 until 1972, the Del Amo Facility site was a center of large-scale industrial activities. Originally built to produce synthetic rubber during World War II and owned by the United States government, the 280-acre operation consisted of a styrene plant operated by Dow Chemical Co., a butadiene plant operated by Shell Oil Co., and a synthetic rubber plant operated by U.S. Rubber Co., Goodyear Tire & Rubber Co., and others. In 1955, the U.S. Government sold all three plants to Shell Oil Company and Shell continued to operate these plants until 1971. Synthetic rubber was produced by manufacturing styrene and butadiene separately, piping them to the rubber plant, and then mixing the two together. Within each facility, wastes from the production processes were directed into separator units. Settled sludge from the separator units was disposed of either off site or in a waste disposal area located on site. Six unlined pits and three unlined evaporation ponds made up the 4-acre on-site disposal area. Upon closure in 1972, the unlined pits and ponds that were still open were covered with soil.

Most of the 280-acre facility has since been developed as an industrial park.

In 1984, contamination was discovered in the waste pit disposal area and underlying soils. Groundwater located beneath the site is heavily contaminated, but is not presently used as a source of drinking water. The deeper drinking water aquifer supplies 34,000 people located within 4 miles of the site. Today, the 4-acre waste pit disposal area is sealed with a RCRA-equivalent cap, and the waste pit area is undeveloped.

The Del Amo Facility is bounded to the south by residences and to the west, north, and east by industrial and commercial facilities. Approximately 17,600 people live within 1 mile of the site.

Contaminants and Risks

Contaminated Media

Groundwater

Soil and Sludges

Groundwater and soils are contaminated with volatile organic compounds (VOCs), polynuclear aromatic hydrocarbons (PAHs), and minor amounts of pesticides, PCBs, and heavy metals. Floating product has been identified on top of the water table at various locations on the site.

The significant chemicals found in the soil were benzene, tetrachloroethene, isopropyltoluene, trichloroethene, benzo(a)pyrene, endeno(1,2,3-cd)pyrene, benzo(b)fluoranthene, 4,4-DDT, n-nitrosodiphenylamine, arsenic and copper.

On-line Environmental Data
The environmental data gathered during the site investigation is available on-line.

Investigation and Cleanup Activities

This site is being addressed in three long-term remedial phases called Operable Units (OU). The three phases will focus on cleanup of the Waste Pit area, the rest of the former facility area soils, and the groundwater.

Site Studies

Soil and NAPL (OU1): In 1992, under EPA oversight, the potentially responsible parties began an investigation into the nature and extent of contamination at the entire site. This investigation included soil sampling, NAPL analyses, soil gas sampling, groundwater sampling, and indoor air sampling within existing buildings. The investigation was completed in 2004, and the final "Remedial Investigation Report" was completed in June 2007. The data was used to conduct a risk assessment, which was completed in February 2006 and a feasibility study, which was completed in 2010. A proposed clean-up plan was issued for public comment in June 2010, and a final clean-up decision was made in September 2011. Both the proposed clean-up plan ("Proposed Plan") and the final clean-up decision ("Record of Decision") are provided in the "Documents and Reports" section below, the Proposed Plan being in the "Fact Sheet" subsection, dated 6/10/10, and the Record of Decision being in the subsection by the same name, dated 9/30/11.

INSTITUTIONAL CONTROLS PILOT PROGRAM
Beginning in February 2008, U.S. EPA implemented an Institutional Controls Pilot Program in cooperation with the California Department of Toxic Substances Control (DTSC), the City of Los Angeles Department of Building and Safety (LADBS) and the City of Los Angeles Department of City Planning. The Institutional Controls Pilot Program involves an environmental review process prior to proceeding with any planned construction activities, for specific parcels located within the Del Amo Superfund Site that have been identified by the U.S. EPA. See the fact sheet below, in the "Site Documents and Reports" section, for further details.

Cleanup Ongoing

Waste Pit Area (OU2): In 1992, under EPA oversight, the potentially responsible parties also began a focussed investigation to determine the nature and extent of contamination and alternative cleanup remedies for the Waste Pit area. This investigation was completed in December 1996, and EPA signed the Record of Decision (ROD), determining the remediation of the Waste Pits, on September 5, 1997. Two Explanations of Significant Differences (ESDs) were also issued, the first in August 2002 and the second in August 2006.

The remedy was built in 2 phases. First, in 1999 the cap and vapor extraction wells were built. Then, in 2006, the SVE/in-situ bioventing system was built.

EPA signed an Order directing Shell Oil Company and Dow Chemical Company to design the cap and soil vapor extraction (SVE) system as described in the ROD. The U.S. General Services Administration was also named on the Order. The first phase of this design work was completed in early 1999, including the cap and vapor wells. EPA issued another Order directing Shell Oil, Dow Chemical, Michelin, Goodyear, and the U.S. General Services Administration to construct the cap systems that were designed. Shell agreed to conduct this work and began in May 1999. Construction of the cap was completed in February 2000. The cap contains a system to capture vapors that rise up from the waste pits and to remove the contamination from them. The cap is currently being maintained and the vapor capture and treatment system in the cap is being operated by Shell Oil Company.

The soil vapor extraction wells were installed when the cap was built, but the system to treat the extracted vapors was not built at that time. In March 1999, EPA began a public involvement process to receive input on which technology to use to treat the contaminated vapors extracted by the SVE system. EPA first decided to pursue resin adsorption with on site regeneration technology and had Shell Oil conduct a pilot test of this technology (conducted in May and June, 2003). After reviewing the results, Shell proposed a different approach altogether, adding an "in-situ bioventing" component to the SVE system.

The new approach, called "SVE/In-Situ Bioventing," consists of slowly extracting contaminated vapors, adding oxygen to most of the extracted vapors and re-injecting them back into the ground, and sending the rest of them through a carbon adsorption unit. The re-injected vapors would be recaptured by our extraction wells, after bringing additional oxygen to the natural bacteria in the soil. Adding oxygen to the soil enables the natural bacteria to increase their population and digest more contamination, breaking it down into harmless chemicals.

EPA approved Shell's final designs for this SVE/In-Situ Bioventing system in September 2005. Shell's contractor constructed the system in 2006, and the system has been operating since August 2006. Through 2011, the system removed approximately 103,840 pounds (47,200 kilograms) of benzene via degradation and adsorption. (updated 11/1/12)

In 2005, EPA performed its first 5-Year Review for the Waste Pits Area, and in 2010, EPA performed its second 5-Year Review. Both reviews found that the capping and soil vapor systems are effective in protecting human health and the environment.

Remedy Design

Groundwater (OU3): The 1992 site investigations mentioned above included investigations into the nature and extent of groundwater contamination caused by the site. The groundwater investigations and studies were separated from the rest of the site work in 1995, and were completed and a proposed remediation plan for it was issued in June 1998. These studies were conducted jointly with the neighboring Montrose Superfund site, and the proposed remediation plan was also issued jointly. The Record of Decision (ROD) for the dual-site groundwater remediation was signed in March 1999. The Responsible Parties completed the design for the groundwater clean-up system in the fall of 2012, under an EPA order. Design activities included extensive groundwater modeling and field pumping tests. EPA negotiated an agreement with the PRPs to constructed the groundwater clean-up system. Construction is expected to begin in 2013. (updated 11/1/12)

A health clinic for community members had been established with a grant from the Agency for Toxic Substances and Disease Registry (ATSDR) and was operated for three years. The clinic provided residents with free health examinations, including testing for exposure to chemicals such as benzene and DDT. It also assisted residents with identifying and eliminating possible chemical exposures in the home. The clinic operated from January 1995 to January 1998.

In conjunction with the completion of the Waste Pits studies, Shell Oil Company negotiated an agreement with local residents near the Waste Pits to purchase their homes. Shell then proceeded to demolish the homes and prepare the land for redevelopment as a community park. Shell is currently working to transfer the property to an entity for the purpose of creating a park. The buyout, home demolition, and park development created a buffer zone between the remaining residences and future remediation activities at the Waste Pits, in order to lessen any disturbance these activities may cause.

Cleanup Results to Date

At the Waste Pits area, the chosen remedy (in the official Record of Decision document) has been constructed and is operating. The cap portion of the remedy was been built in 1999 and has been in operation since January 2000. The soil vapor extraction (SVE) system was partially installed in 1999 and completed in 2006 as an SVE and in-situ bioventing system (SVE/IBT). The system has been operating since August 2006. From August 2006 to December 2009, the SVE/IBT system removed approximately 70,431 pounds (31,946 kilograms) of benzene via degradation and adsorption.

In another location within the site, Shell and Dow conducted a pilot study of a technology known as hydraulic extraction, during which time they have extracted approximately 20 gallons of pure product contamination.

Potentially Responsible Parties

Potentially responsible parties (PRPs) refers to companies that are potentially responsible for generating, transporting, or disposing of the hazardous waste found at the site.

In 1992, EPA signed an Administrative Order on Consent with Shell Oil Company and The Dow Chemical Company to conduct a remedial investigation and feasibility study for the site.

On January 25, 1999, EPA issued Special Notice to the following entities informing them that EPA considers them to be potentially responsible for the response costs incurred in connection with the contamination at the Del Amo Waste Pits: Shell Oil Company, Dow Chemical Company, U.S. General Services Administration, USA Waste Incorporated, Uniroyal Goodrich Tire Company, Michelin North America Incorporated, The Goodyear Tire & Rubber Company, and Minnesota Mining and Manufacturing Company.

On May 3, 1999, EPA issued a Unilateral Administrative Order for Remedial Action at the Waste Pits Area to the following entities, ordering them to implement the remedial action that EPA had chosen: Shell Oil Company, Dow Chemical Company, Michelin North America Incorporated (on behalf of itself and Uniroyal Goodrich Tire Company), Goodyear Tire and Rubber Company, and the U.S. General Services Administration.

EPA has issued "special notice" to the following parties with respect to the groundwater at the Montrose and Del Amo sites. The special notice letter advised the parties that EPA expects them to enter into an agreement to implement the groundwater remedy, as set forth in the record of decision that EPA issued for the Dual Site Groundwater Operable Unit on March 30, 1999.

In 2003, EPA issued unilateral enforcement orders to Montrose Chemical Corporation and Shell Chemical requiring that they perform the steps 1, 2 and 4 of the remedial design, as shown above. In 2008, EPA issued an additional unilateral enforcement order requiring Montrose and Shell to perform the formal pen-to-paper design, step 5 above. Montrose and Shell performed the work under these orders under EPA oversight. EPA performed the computer modeling, step 3, with continual input from Montrose and Shell.

Documents and Reports

Community Involvement

Public Meetings:An informational video was created to provide the public with a description of the SVE/in-situ bioventing system at the Waste Pits area and an update of progress through 2012. The video can be viewed at: http://www.youtube.com/watch?v=ZqsMkf_IY2U&feature=plcp

The Community Involvement Plan dated May 21, 2010, is available. See the above section entitled "Documents and Reports", subsection for "Community Involvement", or just Click HERE. EPA is working with interested shareholders to further modify this plan.